July in the forest with Chris Horne and Barbara Mitcalfe
Rhopalostylis sapida, Nīkau
Trampers may remember the lush groves of nīkau at the West Coast end of the Heaphy Track, a warm, moist site favoured by the species. Out of approximately 2,000 palm species world-wide, nīkau has the twin distinctions of being NZ's only palm species, and the southernmost palm species in the world. On the NZ mainland it is naturally occurring as far south as Whataroa in the west and Banks Peninsula in the east, but Pitt Island in the Chathams is its southernmost and easternmost outpost at 44° south. The only other member of the genus, Rhopalostylis baueri, is found in the Kermadec Islands.
Nīkau's green, approx. 25 cm diameter trunk, ringed with regular scars where the leaves have fallen off, does not taper, and almost never has branches. Because of its smoothness it does not offer a suitable surface for epiphytes to cling to. Reaching to 10 m in height after (estimated) 200 years growth, nīkau have been recorded at well over 20 m high. The stiff, finely-divided leaves are up to 3 m long, with leaflets up to 1 m long. The broad green leaf bases wrap around the top of the trunk, forming a distinctive, bulbous, tulip-shape, out of which, like an upside-down, inside-out, half-furled brolly, the crown of leaves arises in a cluster.
Nīkau have an unmistakable profile, so much so, that even the stately Flora of NZ Volume II refers to nīkau as having a “feather-duster” shape - you get the picture? Nīkau are slow-growing, long-lived trees, taking something like 50 years to develop any trunk at all, and at least 70 years to flower. In summer, like a pink octopus, the inflorescence of hundreds of male and female flowers bursts out of a large, enveloping bract, to lure insects and birds to its nectar. About a year later, the bright scarlet, fingernail-sized fruit, thickly strung on thin stalks like strings of beads, invite kererū and kākā to gorge themselves, thereby helping to ensure the distribution of this handsome endemic palm.
In earlier times the pliable, naturally water-shedding leaves were much used by Māori for thatch- ing whare, mat-making, and leggings for travelling through dense undergrowth, etc. The outer portion of the trunk was used to make storage containers and pots in which to hold water. Often admired by early European artists, nīkau appear in many well-known paintings. Long may they continue to adorn and enrich our landscapes.